The present invention relates to certain novel naphthopyran compounds. More particularly, this invention relates to novel photochromic 6-aryl substituted 3H-naphtho[2,1-b]pyran compounds and to compositions and articles containing such novel naphthopyran compounds. When exposed to light radiation containing ultraviolet rays, such as the ultraviolet radiation in sunlight or the light of a mercury lamp, many photochromic compounds exhibit a reversible change in color. When the ultraviolet radiation is discontinued, such a photochromic compound will return to its original color or colorless state.
Various classes of photochromic compounds have been synthesized and suggested for use in applications in which a sunlight-induced reversible color change or darkening is desired. U.S. Pat. No. 3,567,605 (Becker) describes a series of pyran derivatives, including certain benzopyrans and naphthopyrans. These compounds are described as derivatives of chromene and are reported to undergo a color change, e.g., from colorless to yellow-orange, on irradiation by ultraviolet light at temperatures below about xe2x88x9230xc2x0 C. Irradiation of the compounds with visible light or upon raising the temperature to above about 0xc2x0 C. is reported to reverse the coloration to a colorless state.
U.S. Pat. No. 5,066,818 describes various 3,3-diaryl-3H-naphtho[2,1-b]pyrans as having desirable photochromic properties, i.e., high colorability and acceptable fade, for ophthalmic and other applications. Also disclosed by way of comparative example in the ""818 patent are the isomeric 2,2-diaryl-2H-naphtho[1,2-b]pyrans, which are reported to require unacceptably long periods of time to fade after activation.
U.S. Pat. No. 3,627,690 describes photochromic 2,2-di-substituted-2H-naphtho[1,2-b]pyran compositions containing minor amounts of either a base or weak-to-moderate strength acid. The addition of either an acid or base to the naphthopyran composition is reported to increase the fade rate of the colored naphthopyrans, thereby making them useful in eye protection applications such as sunglasses. It is reported therein further that the fade rate of 2H-naphtho-[1,2-b]pyrans without the aforementioned additives ranges from several hours to many days to reach complete reversion. U.S. Pat. No. 4,818,096 discloses purple/blue coloring photochromic benzo- or naphthopyrans having at the position alpha to the oxygen of the pyran ring a phenyl group having a nitrogen containing substituent in the ortho or para positions.
Certain photochromic naphtho[2,1-b]pyrans having a nitrogen-containing group at the 6 position of the naphthyl portion of the naphthopyran compound have been disclosed. U.S. Pat. No. 5,552,090 describes photochromic naphtho[2,1-b]pyrans substituted at the 6 position of the naphthyl portion of the naphthopyran compound with a nitrogen-containing heterocyclic ring. Photochromic naphtho[2,1-b]pyrans substituted at the 6 position of the naphthyl portion with an alkoxy group or aryloxy group are described in U.S. Pat. No. 5,520,853. U.S. Pat. No. 5,623,005 discloses naphtho[2,1-b]pyrans substituted at the 6 position of the naphthyl portion of the naphthopyran compound with an amino group.
The present invention relates to novel 6-aryl substituted 3H-naphtho[2,1-b]pyran compounds having certain substituents at the 3-position of the pyran ring. Other substituents may also be present optionally at the number 7, 8, 9 or 10 carbon atoms. The naphthopyrans of the present invention have unexpectedly been found to demonstrate a hypsochromic wavelength shift in the visible spectrum at which the maximum absorption of the activated (colored) form of the photochromic compound, i.e., the lambda max (Vis), occurs, thereby resulting in activated colors ranging from yellow to orange. Photochromic compounds of the present invention include compounds that exhibit acceptable photochromic performance properties, i.e., activated intensity, coloration rate and fade rate.
In recent years, photochromic plastic materials, particularly plastic materials for optical applications, have been the subject of considerable attention. In particular, photochromic ophthalmic plastic lenses have been investigated because of the weight advantage they offer, vis-a-vis, glass lenses. Moreover, photochromic transparencies for vehicles, such as cars and airplanes, have been of interest because of the potential safety features that such transparencies offer.
In accordance with the present invention, it has now been discovered that certain novel 6-aryl substituted 3H-naphtho[2,1-b]pyrans having activated colors ranging from yellow to orange may be prepared. These compounds may be described as 6-aryl substituted 3H-naphtho[2,1-b]pyrans having certain substituents at the 3 position of the pyran ring. Certain substituents may also be present at the number 7, 8, 9 or 10 carbon atoms of the naphtho portion of the compounds. These compounds may be represented by the following graphic formula I in which the numbers 1 through 10 within the depicted ring-system represent the numbers of the ring atoms of the naphthopyran: 
In graphic formula I, each R1 and each R2 may be C1-C6 alkyl, C1-C6 alkoxy, chloro or fluoro; and m and n are each the integers 0, 1, or 2. When m and n are 2, each R1 and R2 may be the same or different. More preferably, each R1 and each R2 are C1-C3 alkyl, C1-C3 alkoxy, or fluoro. Most preferably, R1 and R2 are each C1-C3 alkyl or C1-C3 alkoxy.
Ar in graphic formula I may be phenyl, naphthyl, thienyl, benzothienyl, furanyl, benzofuranyl or pyridyl. Preferably Ar is phenyl or naphthyl.
B and Bxe2x80x2 in graphic formula I may each be selected from the group consisting of: (i) the unsubstituted, mono-, di-, and tri-substituted aryl groups, phenyl and naphthyl; (ii) the unsubstituted, mono- and di-substituted heteroaromatic groups pyridyl, furanyl, benzofuran-2-yl, benzofuran-3-yl, thienyl, benzothien-2-yl, benzothien-3-yl, each of said aryl and heteroaromatic substituents in parts (i) and (ii) being selected from the group consisting of di(C1-C6)alkylamino, piperidino, morpholino, pyrryl, C1-C6 alkyl, C1-C6 chloroalkyl, C1-C6 fluoroalkyl, C1-C6 alkoxy, mono(C1-C6)alkoxy(C1-C4)alkyl, acryloxy, methacryloxy, chloro and fluoro; (iii) the groups represented by the following graphic formulae: 
wherein A may be carbon or oxygen and D may be oxygen or substituted nitrogen, provided that when D is substituted nitrogen, A is carbon, said nitrogen substituents being selected from the group consisting of hydrogen, C1-C6 alkyl, and C2-C6 acyl; each R3 is C1-C6 alkyl, C1-C6 alkoxy, hydroxy, chloro or fluoro; R4 and R5 are each hydrogen or C1-C6 alkyl; and p is the integer 0, 1, or 2; (iv) C1-C6 alkyl, C1-C6 chloroalkyl, C1-C6 fluoroalkyl, C1-C6 alkoxy(C1-C4)alkyl, C3-C6 cycloalkyl, mono(C1-C6) alkoxy(C3-C6)cycloalkyl, mono(C1-C6)alkyl(C3-C6)cycloalkyl, chloro(C3-C6)cycloalkyl, and fluoro(C3-C6)cycloalkyl; and (v) the group represented by the following graphic formula: 
wherein X in graphic formula IIC may be hydrogen or C1-C4 alkyl and Z in graphic formula IIC may be selected from the unsubstituted, mono-, and di-substituted members of the group consisting of naphthyl, phenyl, furanyl, and thienyl, each of said group substituents in this part (v) being C1-C4 alkyl, C1-C4 alkoxy, fluoro, or chloro; or (vi) B and Bxe2x80x2 taken together form fluoren-9-ylidene, mono-, or di-substituted fluoren-9-ylidene or form a member selected from the group consisting of saturated C3-C12 spiro-monocyclic hydrocarbon rings, e.g., cyclopropylidene, cyclobutylidene, cyclopentylidene, cyclohexylidene, cycloheptylidene, cyclooctylidene, cyclononylidene, cyclodecylidene cycloundecylidene, cyclododecylidene; saturated C7-C12 spiro-bicyclic hydrocarbon rings, e.g., bicyclo[2.2.1]heptylidene, i.e., norbornylidene, 1,7,7-trimethyl bicyclo[2.2.1]heptylidene, i.e., bornylidene, bicyclo[3.2.1]octylidene, bicyclo[3.3.1]nonan-9-ylidene, bicyclo[4.3.2]undecane, and saturated C7-C12 spiro-tricyclic hydrocarbon rings, e.g., tricyclo[2.2.1.02,6] heptylidene, tricyclo[3.3.1.13,7]decylidene, i.e., adamantylidene, and tricyclo[5.3.1.12,6]dodecylidene, each of said fluoren-9-ylidene substituents being selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, fluoro and chloro.
More preferably, B and Bxe2x80x2 are each selected from the group consisting of: (i) phenyl, mono-substituted phenyl, and di-substituted phenyl; (ii) the unsubstituted, mono- and di-substituted heteroaromatic groups furanyl, benzofuran-2-yl, thienyl, and benzothien-2-yl, each of said phenyl and heteroaromatic substituents being selected from the group consisting of di(C1-C3)alkylamino, piperidino, morpholino, pyrryl, C1-C3 alkyl, C1-C3 chloroalkyl, C1-C3 fluoroalkyl, C1-C3 alkoxy, mono(C1-C3)alkoxy(C1-C3)alkyl, fluoro and chloro; (iii) the groups represented by the graphic formulae IIA and IIB, wherein A is carbon and D is oxygen, R3 is C1-C3 alkyl or C1-C3 alkoxy, R4 and R5 are each hydrogen or C1-C4 alkyl, and p is the integer 0 or 1; (iv) C1-C4 alkyl; and (v) the group represented by the graphic formula IIC wherein X is hydrogen or methyl and Z is phenyl or mono-substituted phenyl, said phenyl substituent being selected from the group consisting of C1-C3 alkyl, C1-C3 alkoxy, and fluoro; or (vi) B and Bxe2x80x2 taken together form fluoren-9-ylidene, mono-substituted fluoren-9-ylidene or a member selected from the group consisting of saturated C3-C8 spiro-monocyclic hydrocarbon rings, saturated C7-C10 spiro-bicyclic hydrocarbon rings, and saturated C7-C10 spiro-tricyclic hydrocarbon rings, said fluoren-9-ylidene substituent being selected from the group consisting of C1-C3 alkyl, C1-C3 alkoxy, fluoro and chloro.
Most preferably, B and Bxe2x80x2 are each selected from the group consisting of (i) phenyl, mono- and di-substituted phenyl, (ii) the unsubstituted, mono- and di-substituted heteroaromatic groups furanyl, benzofuran-2-yl, thienyl, and benzothien-2-yl, each of said phenyl and heteroaromatic substituents being selected from the group consisting of C1-C3 alkyl, C1-C3 alkoxy and fluoro; and (iii) the group represented by graphic formula IIA, wherein A is carbon and D is oxygen, R3 is C1-C3 alkyl or C1-C3 alkoxy, R4 and R5 are each hydrogen or C1-C3 alkyl, and p is the integer 0 or 1; or (iv) B and Bxe2x80x2 taken together form fluoren-9-ylidene, adamantylidene, bornylidene, norbornylidene, or bicyclo[3.3.1]nonan-9-ylidene.
Compounds represented by graphic formula I may be prepared by the following Reactions A through E. Compounds represented by graphic formula V or VA are either purchased or prepared by Friedel-Crafts methods shown in Reaction A using an appropriately substituted or unsubstituted benzoyl chloride of graphic formula IV with a commercially available substituted or unsubstituted benzene compound of graphic formula III. See the publication Friedel-Crafts and Related Reactions, George A. Olah, Interscience Publishers, 1964, Vol. 3, Chapter XXXI (Aromatic Ketone Synthesis), and xe2x80x9cRegioselective Friedel-Crafts Acylation of 1,2,3,4-Tetrahydroquinoline and Related Nitrogen Heterocycles: Effect on NH Protective Groups and Ring Sizexe2x80x9d by Ishihara, Yugi et al, J. Chem. Soc., Perkin Trans. 1, pages 3401 to 3406, 1992.
In Reaction A, the compounds represented by graphic formulae III and IV are dissolved in a solvent, such as carbon disulfide or methylene chloride, and reacted in the presence of a Lewis acid, such as aluminum chloride or tin tetrachloride, to form the corresponding substituted benzophenone represented by graphic formula V (or VA in Reaction B). R and Rxe2x80x2 represent possible phenyl substituents. 
In Reaction B, the substituted or unsubstituted ketone represented by graphic formula VA, in which B and Bxe2x80x2 may represent groups other than substituted or unsubstituted phenyl, as shown in graphic formula V, is reacted with sodium acetylide in a suitable solvent, such as anhydrous tetrahydrofuran (THF), to form the corresponding propargyl alcohol represented by graphic formula VI. Propargyl alcohols having B or Bxe2x80x2 groups other than substituted and unsubstituted phenyl may be prepared from commercially available ketones or ketones prepared via reaction of an acyl halide with a substituted or unsubstituted benzene, naphthalene or heteroaromatic compound. Propargyl alcohols having a B or Bxe2x80x2 group represented by graphic formula IIC may be prepared by the methods described in U.S. Pat. No. 5,274,132, column 2, lines 40 to 68, which disclossure is incorporated herein by reference. 
In Reaction C, the compounds represented by graphic formula VII, some of which are commercially available, are condensed with methanol in the presence of a catalytic amount of an acid such as sulfuric acid to form the corresponding methyl arylacetate represented by graphic formula VIII. 
In Reaction D, compound VIII is reacted with the substituted aryl methyl ketone represented by graphic formula IX in the presence of sodium hydride, resulting in a mixture of the tautomers represented by graphic formulae XA and XB. This reaction is further described in C. R. Hauser et al., Organic Reactions, Vol 8, page 126 (1954). The tautomers are cyclized by heating, e.g., at about 70xc2x0 C., in the presence of acid such as phosphoric acid, to the naphthol represented by graphic formula XI. Cyclization of pyridyl substituted compounds is described generally in C. R. Hauser et al, A New Method for the Synthesis of Certain Benz[a]acridines, J. Amer. Chem. Soc., Vol. 77, pages 3858-3860 (1955). 
In Reaction E, the compound represented by graphic formula XI is coupled with a propargyl alcohol represented by graphic formula VI in the presence of a catalytic amount of an acid, e.g., p-toluene sulfonic acid in a suitable solvent such as chloroform to produce compounds represented by graphic formula I. 
Compounds represented by graphic formula I wherein n is 0 and the xe2x80x94Arxe2x80x94(R2)m group is phenyl, alkyl substituted phenyl or halo substituted phenyl may be prepared by the following Reactions F and G.
In Reaction F, 2-naphthol (graphic formula XII) is reacted with the substituted or unsubstituted benzene represented by graphic formula XIII, wherein R2xe2x80x2 is hydrogen, C1-C6 alkyl, chloro or fluoro, in the presence of aluminum chloride to form the 4-aryl-2-tetralone represented by graphic formula XIV. Compound XIV is aromatized via either a sequence of bromination and dehydrohalogenation or under strong basic conditions in air to form the 4-aryl-2-naphthols represented by graphic formula XV. This procedure is described in V. A. Koptyug et al., Zh. Org. Khim., Vol. 7, pages 2398-2403 (1971). 
In Reaction G, the compound represented by graphic formula XV is coupled with the propargyl alcohol represented by graphic formula VI in the presence of a catalytic amount of an acid, e.g., dodecylbenzene sulfonic acid (DBSA) as in Reaction E to produce compounds represented by graphic formula Ia. 
Compounds represented by graphic formula I may be used in those applications in which organic photochromic substances may be employed, such as optical lenses, e.g., vision correcting ophthalmic lenses and plano lenses, face shields, goggles, visors, camera lenses, windows, automotive windshields, aircraft and automotive transparencies, e.g., T-roofs, sidelights and backlights, plastic films and sheets, textiles and coatings, e.g., coating compositions such as paints, and verification marks on security documents, e.g., documents such as banknotes, passports and drivers"" licenses for which authentication or verification of authenticity may be desired. The 6-aryl or heteroaromatic substituted naphtho[2,1-b]pyrans represented by graphic formula I exhibit color changes from colorless to colors ranging from yellow to orange.
Examples of contemplated naphthopyran compounds within the scope of the invention include the following:
(a) 6-(4-methoxyphenyl)-8,9-dimethoxy-3,3-diphenyl-3H-naphtho [2,1-b]pyran;
(b) 6-(4-methoxyphenyl)-8,9-dimethoxy-3-(2-fluorophenyl)-3-(4-methoxyphenyl)-3H-naphtho[2,1-b]pyran;
(c) 6-phenyl-8,9-dimethoxy-3,3-diphenyl-3H-naphtho[2,1-b]pyran;
(d) 6-phenyl-8,9-dimethoxy-3-(2-fluorophenyl)-3-(4-methoxyphenyl)-3H-naphtho[2,1-b]pyran.
(e) 6-(4-methylphenyl)-3-(2-fluorophenyl)-3-(4-methoxyphenyl)-3H-naphtho[2,1-b]pyran; and
(f) 6-(4-methylphenyl)-3,3-diphenyl-3H-naphtho[2,1-b]pyran.
It is contemplated that the organic photochromic naphthopyrans of the present invention may be used alone, in combination with other naphthopyrans of the present invention, or in combination with one or more other appropriate complementary organic photochromic materials, i.e., organic photochromic compounds having at least one activated absorption maxima within the range of between about 400 and 700 nanometers (or substances containing same) and which color when activated to an appropriate hue. The photochromic compounds of the present invention may be associated with, e.g., incorporated in, i.e., dissolved or dispersed in, a polymeric organic host material used to prepare photochromic articles.
Other than where otherwise indicated, all numbers expressing wavelengths, quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term xe2x80x9caboutxe2x80x9d.
Examples of complementary organic photochromic compounds include other naphthopyrans, chromenes and oxazines, substituted 2H-phenanthro[4,3-b]pyran and 3H-phenanthro[1,2-b]pyran compounds, benzopyran compounds having substituents at the 2-position of the pyran ring including a dibenzo-fused 5 member heterocyclic compound and a substituted or unsubstituted heterocyclic ring, such as a benzothieno or benzofurano ring fused to the benzene portion of the benzopyrans, spiro(benzindoline)naphthopyrans, spiro(indoline)benzopyrans, spiro(indoline)naphthopyrans, spiro(indoline)quinopyrans, spiro(indoline)pyrans, spiro(indoline)napthoxazines, spiro(indoline)pyridobenzoxazines, spiro,(benzindoline)pyridobenzoxazines, spiro(benzindoline)naphthoxazines, spiro(indoline)benzoxazines, and mixtures of such photochromic compounds. Many of such photochromic compounds are described in the open literature, e.g., U.S. Pat. Nos. 3,562,172; 3,567,605; 3,578,602; 4,215,010; 4,342,668; 4,816,584; 4,818,096; 4,826,977; 4,880,667; 4,931,219; 5,066,818; 5,238,981; 5,274,132; 5,384,077; 5,405,958; 5,429,774; 5,458,814; 5,466,398; 5,514,817; 5,552,090; 5,552,091; 5,565,147; 5,573,712; 5,578,252; 5,645,767 and Japanese Patent Publication 62/195383. Spiro(indoline)pyrans are also described in the text, Techniques in Chemistry, Volume III, xe2x80x9cPhotochromismxe2x80x9d, Chapter 3, Glenn H. Brown, Editor, John Wiley and Sons, Inc., New York, 1971.
Other complementary photochromic substances contemplated are photochromic metal-dithizonates, e.g. mercury dithizonates which are described in, for example, U.S. Pat. No. 3,361,706, fulgides and fulgimides, e.g. the 3-furyl and 3-thienyl fulgides and fulgimides which are described in U.S. Pat. No. 4,931,220 at column 20, line 5 through column 21, line 38.
The disclosures relating to such photochromic compounds in the aforedescribed patents are incorporated herein, in toto, by reference. The photochromic articles of the present invention may contain one photochromic compound or a mixture of photochromic compounds, as desired.
Each of the photochromic substances described herein may be used in amounts (or in a ratio) such that an organic host material to which the photochromic compounds or mixture of compounds is applied or in which they are incorporated exhibits a desired resultant color, e.g., a substantially neutral color when activated with unfiltered sunlight, i.e., as near a neutral color as possible given the colors of the activated photochromic compounds. Neutral gray and neutral brown colors are preferred.
A neutral gray color exhibits a spectrum that has relatively equal absorption in the visible range between 400 and 700 nanometers. A neutral brown color exhibits a spectrum in which the absorption in the 400-550 nanometer range is moderately larger than in the 550-700 nanometer range. An alternative way of describing color is in terms of its chromaticity coordinates, which describe the qualities of a color in addition to its luminance factor, i.e., its chromaticity. In the CIE system, the chromaticity coordinates are obtained by taking the ratios of the tristimulus values to their sum, e.g., x=X/(X+Y+Z) and y=Y/(X+Y+Z). Color as described in the CIE system can be plotted on a chromaticity diagram, usually a plot of the chromaticity coordinates x and y. See pages 47-52 of Principles of Color Technology, by F. W. Billmeyer, Jr., and Max Saltzman, Second Edition, John Wiley and Sons, New York (1981). As used herein, a near neutral color is one in which the chromaticity coordinate values of xe2x80x9cxxe2x80x9d and xe2x80x9cyxe2x80x9d for the color are within the following ranges (D65 illuminant): x=0.260 to 0.400, y=0.280 to 0.400 following activation to 40 percent luminous transmission by exposure to solar radiation (Air Mass 1 or 2).
The amount of photochromic substance or composition containing same applied to or incorporated into a host material is not critical provided that a sufficient amount is used to produce a photochromic effect discernible to the naked eye upon activation. Generally such amount can be described as a photochromic amount. The particular amount used depends often upon the intensity of color desired upon irradiation thereof and upon the method used to incorporate or apply the photochromic substances. Typically, the more photochromic substance applied or incorporated, the greater is the color intensity up to a certain limit.
The relative amounts of the aforesaid photochromic compounds used will vary and depend in part upon the relative intensities of the color of the activated species of such compounds, and the ultimate color desired. Generally, the amount of total photochromic substance incorporated into or applied to a photochromic optical host material may range from 0.05 to 1.0, e.g., from 0.1 to 0.45, milligrams per square centimeter of surface to which the photochromic substance(s) is incorporated or applied.
The photochromic substances of the present invention may be associated with, applied to or incorporated within a host material such as a polymeric organic host material by various methods described in the art. Such methods include dissolving or dispersing the photochromic substance within the host material, e.g., casting it in place by adding the photochromic substance to the monomeric host material prior to polymerization; imbibition of the photochromic substance into the host material by immersion of the host material in a hot solution of the photochromic substance or by thermal transfer; providing the photochromic substance as a separate layer between adjacent layers of the host material, e.g., as a part of a polymeric film; and applying the photochromic substance as part of a coating or film placed on the surface of the host material. The term xe2x80x9cimbibitionxe2x80x9d or xe2x80x9cimbibexe2x80x9d is intended to mean and include permeation of the photochromic substance alone into the host material, solvent assisted transfer of the photochromic substance into a porous polymer, vapor phase transfer, and other such transfer mechanisms.
Compatible (chemically and color-wise) tints, i.e., dyes, may be applied to the host material to achieve a more aesthetic result, for medical reasons, or for reasons of fashion. The particular dye selected will vary and depend on the aforesaid need and result to be achieved. In one embodiment, the dye may be selected to complement the color resulting from the activated photochromic substances, e.g., to achieve a more neutral color or absorb a particular wavelength of incident light. In another embodiment, the dye may be selected to provide a desired hue to the host matrix when the photochromic substances is in an unactivated state.
The host material will usually be transparent, but may be translucent or even opaque. The host material need only be transparent to that portion of the electromagnetic spectrum, which activates the photochromic substance, i.e., that wavelength of ultraviolet (UV) light that produces the open form of the substance and that portion of the visible spectrum that includes the absorption maximum wavelength of the substance in its UV activated form, i.e., the open form. Preferably, the host color should not be such that it masks the color of the activated form of the photochromic substance, i.e., so the change in color is readily apparent to the observer. More preferably, the host material article is a solid transparent or optically clear material, e.g., materials suitable for optical applications, such as plano and ophthalmic lenses, windows, automotive transparencies, e.g., windshields, aircraft transparencies, plastic sheeting, polymeric films, etc.
The photochromic compounds of the present invention may be dissolved in an organic solvent or present in an organic polymeric host. The organic solvent may be selected from the group consisting of benzene, toluene, methyl ethyl ketone, acetone, ethanol, tetrahydrofurfuryl alcohol, N-methyl pyrrolidinone, 2-methoxyethyl ether, xylene, cyclohexane, 3-methyl cyclohexanone, ethyl acetate, tetrahydrofuran, methanol, methyl propinate, ethylene glycol and mixtures thereof. Preferably, the organic solvent is selected from the group consisting of acetone, ethanol, tetrahydrofurfuryl alcohol, 2-methoxyethyl ether, 3-methyl cyclohexanone, N-methyl pyrrolidinone and mixtures thereof.
Preferably, the organic polymeric host material is a solid transparent or optically clear material, e.g., materials suitable for optical applications, such as plano and ophthalmic lenses, windows, automotive transparencies, e.g., windshields, aircraft transparencies, plastic sheeting, polymeric films, etc. Examples of polymeric organic host materials are polymers prepared from individual monomers or mixtures of monomers selected from the following groups:
(a) diacrylate or dimethacrylate compounds represented by graphic formula XVI: 
xe2x80x83wherein R6 and R7 may be the same or different and are hydrogen or methyl, and W is methylene (CH2), and t is an integer of from 1 to 20;
(b) diacrylate or dimethacrylate compounds represented by graphic formula XVII: 
xe2x80x83wherein L is CH2CH(R7) or (CH2)s wherein s is an integer selected from the group consisting of 1, 3 and 4 and v is an integer of from 1 to 50; and
(c) an acrylate or a methacrylate compound having an epoxy group represented by graphic formula XVIII: 
xe2x80x83wherein R9 is hydrogen or methyl.
In graphic formulae XVI, XVII and XVIII, like letters used with respect to the definitions of different substituents have the same meaning.
Examples of diacrylate or dimethacrylate compounds, i.e., di(meth)acrylate, represented by graphic formulae XVI include butanediol di(meth)acrylate, hexanediol di(meth)acrylate and nonanediol di(meth)acrylate; examples of compounds represented by graphic formula XVII include diethylene glycol dimethacrylate, triethylene glycol dimethacrylate and poly(oxyalkylene dimethacrylates), e.g., polyethylene glycol (600) dimethacrylate. Examples of acrylate or methacrylate compounds represented by graphic formula XVIII include glycidyl acrylate and glycidyl methacrylate.
Further examples of polymeric organic host materials which may be used with the photochromic compounds described herein include: polymers, i.e., homopolymers and copolymers, of the monomers and mixtures of monomers represented by graphic formulae XVI, XVII and XVIII, bis(allyl carbonate) monomers, diisopropenyl benzene monomers, ethoxylated bisphenol A dimethacrylate monomers, ethylene glycol bismethacrylate monomers, poly(ethylene glycol) bismethacrylate monomers, ethoxylated phenol bismethacrylate monomers, alkoxylated polyhydric alcohol polyacrylate monomers, such as ethoxylated trimethylol propane triacrylate monomers, urethane acrylate monomers, such as those described in U.S. Pat. No. 5,373,033, and vinylbenzene monomers, such as those described in U.S. Pat. No. 5,475,074 and styrene; polymers, i.e., homopolymers and copolymers, of polyfunctional, e.g., mono-, di- or multi-functional, acrylate and/or methacrylate monomers, poly(C1-C12 alkyl methacrylates), such as poly(methyl methacrylate), poly(alkoxylated phenol methacrylates), cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, poly(vinyl acetate), poly(vinyl alcohol), poly(vinyl chloride), poly(vinylidene chloride), polyurethanes, thermoplastic polycarbonates, polyesters, poly(ethylene terephthalate), polystyrene, poly(alpha methylstyrene), copoly(styrene-methyl methacrylate), copoly(styrene-acrylonitrile), polyvinylbutyral and polymers, i.e., homopolymers and copolymers, of diallylidene pentaerythritol, particularly copolymers with polyol (allyl carbonate) monomers, e.g., diethylene glycol bis(allyl carbonate), and acrylate monomers, e.g., ethyl acrylate, butyl acrylate.
Transparent copolymers and blends of transparent polymers are also suitable as host materials. Preferably, the host material is an optically clear polymerized organic material prepared from a thermoplastic polycarbonate resin, such as the carbonate-linked resin derived from bisphenol A and phosgene, which is sold under the trademark, LEXAN; a polyester, such as the material sold under the trademark, MYLAR; a poly(methyl methacrylate), such as the material sold under the trademark, PLEXIGLAS; polymerizates of a polyol(allyl carbonate) monomer, especially diethylene glycol bis(allyl carbonate), which monomer is sold under the trademark CR-39, and polymerizates of copolymers of a polyol (allyl carbonate), e.g., diethylene glycol bis(allyl carbonate), with other copolymerizable monomeric materials, such as copolymers with vinyl acetate, e.g., copolymers of from 80-90 percent diethylene glycol bis(allyl carbonate) and 10-20 percent vinyl acetate, particularly 80-85 percent of the bis(allyl carbonate) and 15-20 percent vinyl acetate, and copolymers with a polyurethane having terminal diacrylate functionality, as described in U.S. Pat. Nos. 4,360,653 and 4,994,208; and copolymers with aliphatic urethanes, the terminal portion of which contain allyl or acrylyl functional groups, as described in U.S. Pat. No. 5,200,483; poly(vinyl acetate), polyvinylbutyral, polyurethane, polymers of members of the group consisting of diethylene glycol dimethacrylate monomers, diisopropenyl benzene monomers, ethoxylated bisphenol A dimethacrylate monomers, ethylene glycol bismethacrylate monomers, poly(ethylene glycol) bismethacrylate monomers, ethoxylated phenol bismethacrylate monomers and ethoxylated trimethylol propane triacrylate monomers; cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, polystyrene and copolymers of styrene with methyl methacrylate, vinyl acetate and acrylonitrile.
More particularly, contemplated is use of the photochromic naphthopyrans of the present invention with optical organic resin monomers used to produce optically clear polymerizates, i.e., materials suitable for optical applications, such as for example plano and ophthalmic lenses, windows, and automotive transparencies. Such optically clear polymerizates may have a refractive index that may range from about 1.48 to about 1.75, e.g., from about 1.495 to about 1.66. Specifically contemplated are optical resins sold by PPG Industries, Inc. under the CR- designation, e.g., CR-307 and CR-407.
The present invention is more particularly described in the following examples which are intended as illustrative only, since numerous modifications and variations therein will be apparent to those skilled in the art.